Heat exchanger, method for its production as well as several devices comprising such a heat exchanger

ABSTRACT

Heat exchanger  1  for removing heat from a medium with at least one serpentine-shaped wing tube  20  arranged in a housing, the linear wing section  30  of which is arranged such that the wing  24  of the wing section  30  encloses an angle in the range of 10°≦α≦30° with a flow direction S.

1. FIELD OF THE INVENTION

The present invention is related to a heat exchanger for removing heatfrom a medium, a serpentine-shaped wing tube as an essential part ofsuch a heat exchanger, a method for producing such a serpentine-shapedwing tube as well as a method for producing the above-mentioned heatexchanger.

2. BACKGROUND OF THE INVENTION

Heat exchangers are generally known in the prior art. They are used incooling systems and air conditioners or air conditioning systems towithdraw heat from a heated medium and to dissipate it to thesurrounding. Based on this functionality, the heat exchangers are alsodenoted as condenser or evaporator based on the transformation of themedium to be cooled therein.

Such heat exchangers usually consist of at least two side walls arrangedoppositely to each other and between which a grid structure is arrangedwhich consists of tubes. These tubes form a flow path through which amedium to be cooled may be directed. The outside of the tubes is forexample flowed around by an air flow which is directed to the tubearrangement by means of a fan.

Depending on the type of tube arrangement of the tubes, which is exposedto the cooling air or gas flow, the medium directed within the tubes iscooled. For increasing the heat absorption of the flowing around medium,for example the flowed around tube surface is increased. For thispurpose, the tubes of the heat exchanger are provided with radiallyprotruding wings, so-called wing tubes, as they are exemplarilydisclosed in WO 2009/068979. Such wing tubes consist of thermallyconductive metal or alloys thereof as for example steel, steel alloy,copper, copper alloy, aluminum and aluminum alloys. The wing tubes areeither produced by rolling or by metal extrusion.

In the heat exchanger of WO 2009/068979, several linear wing tubes arearranged between two opposite side walls. In the portion of thesidewalls, the linear wing tubes are connected to each other via curvedcoupling parts, respectively. Such coupling parts are solderedindividually to the two linear wing tubes to be connected for producinga liquid-tight or gas-tight connection between the two linear wingtubes. This production method of the heat exchanger is, due to theplurality of work steps, labour-intensive and thus expensive. Further,the linear wing tubes are arranged even relative to each other whichleads to a shadowing of adjacent wing tubes and thus to a reducedefficiency of the heat exchanger. A further disadvantage is that in atoo close-meshed arrangement of the tubes of the heat exchanger acontamination may occur which has to be removed regularly. This isespecially obvious when lamellar structures are used in the heatexchanger. Accordingly, high maintenance efforts are required,respectively, in order to clean the heat exchanger regularly.

It is thus the object of the present invention to provide a heatexchanger with improved efficiency, a lower amount of maintenancerequired and which is based on a simplified production method comparedto the prior art.

3. SUMMARY OF THE PRESENT INVENTION

The present invention comprises a heat exchanger for removing heat froma medium, wherein the heat exchanger has the following features: atleast two outer walls defining an opening therebetween by means of whicha gas flow is directable into a flow direction, at least a first and asecond serpentine-shaped wing tube consisting of a tube and at least twowings, which protrude radially therefrom, preferably oppositely, whereinthe wing tube has at least two linear wing sections coupled viawing-less curved tube sections, respectively, the wing sections of theat least first and second wing tube are arranged in at least one tubeplane per wing tube, respectively, wherein the tube plane is orientatedvertically to the flow direction, wherein the wings of the wing sectionsof at least the first wing tube are arranged in at least a plurality offirst wing planes arranged parallel to each other, which are arranged ina defined angle in the range of 10°≦α≦30° with respect to the flowdirection.

The construction of the heat exchanger according to the invention isbased on at least one wing tube, which is curved in the shape of a wavyline or a serpentine, through which a medium to be cooled may bedirected. This serpentine-shaped curved wing tube comprises linear wingsections, which are exposed to the flowing around and cooling medium inthe future heat exchanger, as well as curved wingless tube sections,which couple two adjacent linear wing sections to each other. As theserpentine shaped wing tube is preferably formed integrally, accordingto one embodiment by the extrusion of aluminum or an aluminum alloy,also the linear wing sections and the wingless curved tube sections arecoupled integrally to each other and thus require no additional couplingmethods, such as for example hard soldering, during the production ofthe heat exchanger. Further, preferably the linear wing sections of theserpentine-shaped wing tube are arranged in at least one tube planeperpendicular to the flow direction for ensuring an orderly gridstructure of the heat exchanger and thus a flowing of the cooling mediumagainst a surface of the heat exchanger as large as possible.

For providing a sufficient large surface by the serpentine-shaped wingtube for flowing against by the cooling medium, the wings of the wingsections of the serpentine-shaped wing tube are aligned in a definedangle with respect to the flow direction of the inflowing cooling mediumor in a defined angle with respect to the normal of the tube plane inwhich the wing sections are arranged. This defined angle of the wings ofthe wing sections reaches from a range of 10°≦α≦30°. By means of thevariation of the angle of the wings of the wing sections, the size ofthe flowed against surface of the heat exchanger is adjustable on theone hand. Further, it is possible to provide equal or different flowconditions within the heat exchanger. Due to this variability, forexample a shadowing of wing sections arranged downstream in flowdirection may be reduced, which in turn improves the efficiency of theheat exchanger.

According to a preferred embodiment of the present invention, the wingsections of the at least first and second serpentine-shaped wing tube ofthe heat exchanger are arranged in two tube planes per wing tube suchthat adjacent wing sections of a wing tube are arranged in differenttube planes. Further, it is preferred to arrange the wings of the wingsections of the second wing tube in at least a plurality of second wingplanes, which are arranged parallel to each other and which are arrangedin a second defined angle in the range of 10°≦β≦30° with respect to theflow direction. In a further preferred embodiment of this arrangement,the first or the second or the first and the second defined angle lie ina range of 10°≦α, β≦20°, further preferred in a range of 12°≦α, β≦18°and even more preferred at an angle of 15°.

Depending on the above-mentioned angle ranges, the surface arrangedagainst the flowing medium, for example air, varies in its size and alsothe turbulence of the inflowing cooling medium in the heat exchangervaries so that the withdrawal of heat from the medium directed in thewing tubes is successively increased. It has become apparent that anincreased efficiency of the heat exchanger may be achieved with asetting of the wings of the wing sections in an angle of 12°-18° andeven better of 15° with respect to the flow direction or the normal ofthe tube plane. In general, already adequate heat exchanger results areachievable in an angle range of the wing sections of 10°-30°.

In another arrangement of the above-described embodiments it is furtherpreferred to provide a plurality of wings, which protrude in radialdirection and are formed curved out of the wing planes. This preferredshaping of the wings, which is similar to an aircraft wing when viewedin the cross sectional side view, supports the heat exchange with themedium flowing against the wing tube. In this context, it is especiallypreferred that the wings of the wing tube which are arranged opposite toeach other are curved in opposite directions. For further supporting theheat exchange between the surrounding and the medium contained in thewing tube it is also preferred to provide a plurality of recesses on aninner side of the tube of the wing tube which enlarge the surface of theinner side of the tube of the wing tube. Preferably, these recesses onthe inner side of the tube extend in longitudinal direction of the wingtube whereas webs, which are arranged adjacent to these recesses,protrude radially into the interior of the wing tube. These webs mayhave different shapes as for example a square or a roundedcross-section.

According to a further preferred embodiment of the heat exchangeraccording to the invention, the wing sections of the at least first andsecond wing tubes are arranged in flow direction next to each otherand/or displaced with respect each other. Furthermore, and according toa further embodiment of the present invention, at least three or fourserpentine-shaped wing tubes are used, the wing sections of which arearranged in at least one tube plane per wing tube, respectively.

For providing a compact and powerful heat exchanger, it is furtherpreferred to arrange the wingless curved sections of theserpentine-shaped wing tube at a side of the serpentine-shaped wingtube, respectively, in a plurality of bending planes, which are parallelto each other and which extend in an angle with respect to the tubeplane of the wing tube which corresponds to the angle of the wing planerelated to the flow direction. This is especially advantageous, in casethe serpentine-shaped wing tubes are according to a further preferredembodiment of the present invention integral, preferably extruded, wingtubes preferably from aluminum or aluminum alloy. Based on the abovedescribed shape of the wing tube consisting of wing sections andwingless curved sections it is then possible to insert the winglesscurved sections in elongated holes in the sidewalls of the heatexchanger, which are provided therefore, and to retain them therein.Further fastening methods or couplings methods between the curvedsections and the wing sections are thus at first not required in casethe serpentine-shaped wing tubes are realized as integral wing tubes.

The present invention discloses further a serpentine-shaped wing tubefor the above described heat exchanger for removing heat from a mediumdirected within the serpentine-shaped wing tube. This serpentine-shapedwing tube comprises the following features: a tube and at least twowings protruding radially therefrom, preferably oppositely, wherein thewing tube comprises at least three linear wing sections coupled viawingless curved tube sections, wherein the wing sections of theserpentine-shaped wing tube are arranged in at least one tube plane,wherein the wings of the wing sections are arranged in at least aplurality of first wing planes, which are arranged parallel to eachother and which are arranged in a defined angle in the range of10°≦α≦30° with respect to a normal of the first tube plane. Thepreferred constructive characteristics of the serpentine-shaped wingtube were already discussed above in combination with the preferred heatexchanger according to the invention.

The present invention discloses further a method for producing aserpentine-shaped wing tube, comprising the following steps: providing alinear wing tube consisting of a tube and at least two wings protrudingradially therefrom, preferably oppositely, removing the wings inspecific sub-sections so that linear wingless tube sections adjacent towing sections occur, bending the wingless tube sections in a 180°-curveso that the wing-sections are arranged in one plane and the wings of thewing sections are orientated almost vertically to this plane, andtwisting of U-shaped sections adjacent to each other which consist eachof two adjacent wing sections coupled via a curved wingless tube sectionagainst each other so that at least a first wing section of the U-shapedsection is arranged in a first tube plane and the wings of the wingsections are arranged in at least a plurality of wing planes,respectively, wherein the wing planes are arranged parallel to eachother and in a defined angle in the range of 10°≦α≦30° with respect to anormal of the first tube plane.

According to the invention, the serpentine-shaped wing tubes forming thecore of the heat exchanger are produced from a one piece wing tube. Thelinear wing sections, for example, are already present subsequent to theextrusion of the wing tubes from aluminum or an aluminum alloy accordingto a preferred embodiment of the present invention. The future curvedwingless tube sections are created by removing the wings from thepresent wing tube. For providing a clear alignment and structuredarrangement of the wing sections in the future heat exchanger, adjacentwing sections are always arranged in pairs in U-shaped sections. Thesections arranged in pairs are coupled to each other via the winglesstube sections and the respective bending thereof For producing aserpentine-shaped tube having an alignment of the wings in a specificangle with respect to the future flow direction of the cooling medium,the U-shaped sections are twisted against each other out of a commonplane of the serpentine-shaped wing tube such that the wings of the wingsections are arranged with respect to the later flow direction in anangle of 10°≦α≦30°. It is preferred to twist the U-shaped sections ofthe serpentine-shaped wing tubes against each other so that the adjacentwing sections of U-shaped sections are arranged in a first and a secondtube plane. The wings of the wing sections of the first and the secondtube plane are arranged in an angle range of 10°≦α≦30°, with respect tothe normal of the tube plane or the flow direction of the futureinflowing cooling medium. As this angle is always related to thesmallest rotation angle between the wing and the normal of the tubeplane or the flow direction, the wings may be arranged in a mathematicalangle range of 10°≦α≦30°and −30°≦α≦−10° around the flow direction or thenormal of the tube plane, which will be discussed in the followingindependently from the algebraic sign as angle in the range of 10°-30°.This understanding also applies to the remaining angles discussed in thefollowing.

The present invention comprises further a method for producing theabove-described heat exchanger comprising the following steps: providinga housing consisting of at least two opposite side walls having aplurality of elongated holes, preferably arranged parallel to eachother, inserting at least one serpentine-shaped wing tube into theplurality of elongated holes of the opposite side walls such that aplurality of curved wingless tube sections is in engagement with theplurality of elongated holes, and coupling a coupling conduit to each ofthe open ends of the serpentine-shaped wing tube. According to a furtherpreferred method step, two, three, four or more serpentine-shaped wingtubes are inserted into the plurality of elongated holes and theserpentine-shaped wing tubes are coupled to each other. Preferably, andin the production method, the wing tube is provided with recesses on theinner side of the tube and/or with curved wings as they were alreadyexplained above.

The present invention comprises further an air conditioner, a coolingdevice as well as a solar heat device having a heat exchanger asdescribed above. A further application of the present invention is adryer having a heat exchanger as described above. Preferably, in such adryer, the heat exchanger is used in combination with a heat pumpsystem. In the most general sense, the present invention is thusdirected to the usage of the preferred heat exchanger according to theinvention as condenser and/or evaporator in different devices.

4. SHORT DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The preferred embodiments of the present invention will now be describedin detail with respect to the accompanying drawings. It shows:

FIG. 1 a perspective view of a preferred heat exchanger according to theinvention,

FIG. 2 a side view of the heat exchanger of FIG. 1,

FIG. 3 a further preferred embodiment of the heat exchanger according tothe invention,

FIG. 4 a side view of the heat exchanger of FIG. 3,

FIG. 5 an enlarged depiction of the encircled section of FIG. 4,

FIG. 6 a top view on a preferred embodiment of a serpentine-shaped wingtube,

FIG. 7 a side view of the serpentine-shaped wing tube of FIG. 6,

FIG. 8 an enlarged depiction of the encircled section of FIG. 7,

FIG. 9 a further preferred embodiment of a serpentine-shaped wing tube,

FIG. 10 a side view of the serpentine-shaped wing tube of FIG. 9,

FIG. 11 an enlarged depiction of the encircled portion of FIG. 10,

FIG. 12 a preferred embodiment of a serpentine-shaped wing tube havingthe wing sections in only one tube plane,

FIG. 13 a preferred embodiment of a serpentine-shaped wing tube havingthe wing sections in a first and in a second tube plane,

FIG. 14 installation sequences according to a preferred method forproducing the heat exchanger,

FIG. 15 a preferred correlation between the energy releasing of the heatexchanger depending on the angle orientation of the wings of theserpentine-shaped wing tube,

FIG. 16 a preferred normalized energy removal of heat exchangers ofdifferent constructions depending on the angle of the wings with respectto the flow direction in case the arrangement of the wing sections isvaried with respect to each other,

FIG. 17 an enlarged depiction of a preferred wing tube having wingsections and a wingless tube section,

FIG. 18 a flow chart of a preferred production method of aserpentine-shaped wing tube,

FIG. 19 a flow chart of a preferred production method of a heatexchanger,

FIG. 20 a cross-sectional view of a preferred embodiment of a wing tubeaccording to the invention and

FIG. 21 a schematic cross-sectional view of a heat exchanger withpreferred wing tubes having curved wings.

5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 and 3, preferred embodiments of the heat exchanger 1according to the invention are shown. The heat exchanger 1 comprises ahousing having at least two oppositely arranged sidewalls 10.Preferably, the housing comprises four sidewalls 10 arranged as arectangle as well as a front plate 12 defining an inlet or outletopening 14. Opposite to the inlet or outlet opening 14, the housing isopen or it comprises a further opening (not shown). Based on thisconstruction, air or any other cooling gaseous medium may be directedthrough the housing in a flow direction S (cf. FIG. 1). According to anembodiment, the sidewalls 10 consist of sheet metal with a painted orotherwise corrosion resistant coated surface. In this manner, thehousing resists the thermal stresses and strains as well as the stressesand strains due to humidity. In case coated or painted sheet metals areused for producing the housing, they are preferably coupled to eachother via clinching or riveting for avoiding a damaging of the sheetmetal or the protective coating or surface finish thereon. It iscertainly also preferred to produce the housing from plastic as long asthe requirements with respect to stability and durability of the housingare fulfilled.

Usually, air is directed through the housing in flow direction S. Tothis end, the air is moved in flow direction S, for example sucked bymeans of a respective fan (not shown), which is preferably arranged atthe backside of the heat exchanger 1. It is also conceivable to blow airthrough the heat exchanger 1 by means of the fan.

The heat exchanger 1 comprises a plurality of wing tubes 20 which arearranged within the housing of the heat exchanger. Preferably, the wingtubes 20 protrude transversely to the flow direction S and they arearranged in regular distances in a grid-like structure. FIG. 17 showsexemplarily a preferred embodiment of a wing tube 20 consisting of atube 22 and wings 24 radially protruding therefrom. Preferably, thewings 24 are arranged oppositely to each other and they are formedlinearly. It is also conceivable to arrange the wings 24 in a wavy orbroken structure or to arrange more than two circumferentiallydistributed radial wings 24 at the tube 22.

According to a preferred embodiment, the wing tube 20 consists ofextruded aluminum or an aluminum alloy. The wing tube 20 may also beproduced in another way as by extrusion, as for example by rolling.Further, and for producing such wing tubes 20, all heat conductivematerials are appropriate with which a wing tube 20 may be produced.

The wing tube 20 is hollow in the interior so that a medium, forexample, liquids or gases may be directed through the wing tube 20. Forexample, in case air flows in flow direction S through the heatexchanger 1 and thus past the wing tube 20, heat is withdrawn from themedium directed within the wing tube 20 by means of the air flow andremoved to the surrounding. The wings 24 of the wing tube 20 provide atthis a larger surface so that the air flowing by may withdraw heat fromthe medium in the wing tube 20, provided that the air temperature islower than the temperature of the medium in the wing tube 20 (cf. FIG.17).

Preferably, the wing tube 20 is produced from aluminum, an aluminumalloy or any other heat-conductive material, preferably metal (cf. FIG.18). According to a preferred embodiment for producing such wing tubes,the wing tube 20 is extruded (SI). According to an embodiment, the tube22 has an outer diameter of about 8 mm and a wall thickness of about 0.7mm. The wings 24 protrude in radial direction oppositely to each otherfor 7 mm, respectively. Thus, the wing tube 20 with wings 24 has anoverall width of about 22 mm. According to a further preferredembodiment of the present invention, other than the above describedmaterials and dimensions are used for producing the wing tube 20,provided that they correspond to the requirements for the heat exchanger1.

For supporting the heat exchange between the surrounding and the mediumwithin the wing tube 24, preferably the surface on the inner side of thetube of the wing tube 24 is increased. For this purpose, a plurality ofrecesses 25 a is introduced in the inner side of the tube, which extendin radial direction according to a preferred embodiment shown in FIG.20. Adjacent to the recesses 25 a, preferably webs 25 b protruderadially inwards into the interior of the wing tube 24. These webs 25 bas well as the recesses 25 a have preferably different cross-sectionalshapes, which are determined for example by the production method or thesize of the surface on the inner side of the tube which has to beachieved. Therefore, it is conceivable that the recesses 25 a and/or thewebs 25 b are formed with a rectangular, triangular, polygonal orrounded cross-sectional design.

Once the wing tube 20 has been produced as a continuous part (SI), thewings 24 are removed in specific sub-sections in longitudinal directionof the wing tube 20. As a consequence, wing sections 30 and winglesstube sections 40 result, as it is shown in FIG. 17. As can be seen basedon FIGS. 1 and 3, the wing sections 30 are arranged in the heatexchanger 1 substantially between the side-walls 10 and are flowedaround in flow direction S. The wingless tube sections 40 are formedcurved and are arranged in the section of the sidewalls 10 to retain thewing tube 20 within the housing of the heat exchanger 1.

Once the wing tube 20 has been produced and the wings 24 were removed insub-sections, a linear wing tube 20 consisting of linear wing sections30 and linear wingless tube sections 40 is present. Subsequently, thewingless tube sections 40 are bended by 180° so that a serpentine-shapedwing tube 20 is present. Within the serpentine-shaped wing tube,U-shaped sections 26 result having two wing sections 30 adjacent to eachother, respectively, which are coupled to each other via a curvedwingless tube section 40. The serpentine-shaped wing tube 20 ispreferably bended (SIII) so that the wing section 30 is arranged in acommon tube plane R1 and the wings 24 are orientated transversely to thetube plane R1.

Subsequently, U-shaped sections 26 a, 26 b, 26 c adjacent to each otherare twisted (SIV) such that a part of the tube sections 30 extendingparallel to each other are arranged outside the tube plane R1 (cf. FIGS.7, 8, 10, 11, 13). According to a preferred embodiment shown in FIG. 13,the U-shaped sections 26 a, 26 b, 26 c are twisted around theirlongitudinally extending main axis such that the U-shaped sections 26 a,26 b, 26 c are arranged parallel to each other thereafter. In apreferred embodiment of this parallel arrangement of the U-shapedsections 26 a-26 c, one tube section 30 of a U-shaped section 26 a is intube plane R1 and the other tube section 30 of the U-shaped section 26 ais in tube plane R2, respectively. It is also preferred to twist theU-shaped sections 26 a-26 c such that the tube sections 30 are arrangedin further tube planes (not shown). Following the installation of theserpentine-shaped wing tube 20 in the housing of the heat exchanger 1,the tube planes R1 and R2 and thus the tube sections 30 are arrangedpreferably vertical to the flow direction S as can be seen for examplein FIG. 1.

Preferably, at least one serpentine-shaped wing tube 20 is arranged in aheat exchanger 1. According to further preferred embodiments, three,four or more serpentine-shaped wing tubes 20 a, 20 b, 20 c, 20 d areinstalled in the housing of the heat exchanger 1, as can be seen inFIGS. 1, 2, 4, 14.

While the wing sections 30 extending transversely to the flow directionS are arranged between the side walls 10, the wingless curved tubesections 40 are arranged and retained in an elongated hole 16,respectively (cf. FIG. 2). The elongated holes 16 correspond to the sizeof the wingless curved tube sections 40 and the inclination thereofcompared to one of the tube planes R1, R2. For retaining the at leastone serpentine-shaped wing tube 20 in the heat exchanger 1, the winglesscurved tube sections 40 are inserted and retained in both oppositesidewalls 10 in the elongated holes 16 provided therefore (SIV). Asthese sidewalls 10 are fixed in the heat exchanger 1 in a defineddistance with respect to each other, the serpentine-shaped wing tubes 20are not able to release itself from the elongated holes 16 and are thuspermanently mounted in an easy manner.

As can be seen based on FIG. 4 depicting a cross-section along the line4-4 in FIG. 3, four serpentine-shaped wing tubes 20 are installed in theheat exchanger 1. The wing sections 30 of each serpentine-shaped wingtube 20 are arranged in two tube planes R1, R2, respectively. Further,the wing sections 30 of different serpentine-shaped wing tubes 20, whichare arranged adjacent in flow direction S, are arranged next to eachother. It is also preferred to arrange the wing sections 30 displacedfrom each other to vary the flow around thereof (not shown).

Once the housing consisting of the at least two sidewalls 10 wasprovided (step H1), the serpentine-shaped wing tubes 20 are inserted inthe elongated holes 16 in the sidewalls 10 (step H2). Subsequently, thesidewalls 10 are fastened to each other via at least one further housingwall, for example the front plate 12, or they are fastened on a baseplate. In this way, it is ensured that the sidewalls 10 are fixed in adefined distance with respect to each other so that theserpentine-shaped wing tubes 20 may not drop out of the elongated holes16 (cf. FIG. 14). Thereafter, adjacent serpentine-shaped wing tubes 20are coupled to each other to provide one continuous flow path of themedium to be cooled through all serpentine-shaped wing tubes 20 whichare fastened in the heat exchanger 1 (step H3) (cf. FIG. 19).

Subsequently, coupling conduits are coupled, preferably soldered, to theinlet and the outlet of the serpentine-shaped wing tubes 20 coupled toeach other to be able to integrate the heat exchanger 1 into a coolingdevice, an air conditioner or a solar heat device (step H4). Accordingto a preferred embodiment of the present invention, the heat exchanger 1is provided with an own fan (not shown) by means of which for examplecooling air can be directed over the wing sections 30, i.e. sucked orblown (cf. FIG. 8).

As can be seen from FIG. 12, the wings 24 are aligned vertically to thetube plane R1. Once the U-shaped sections 26 a-26 c have been twistedaround the central longitudinal axis, the wings are arranged in aplurality of wing planes F. According to a preferred embodiment shown inFIGS. 6 to 8, the wings 24 of a serpentine-shaped wing tube 20 arearranged in a plurality of wing planes F1, which are arranged parallelto each other. The wing planes F1 and thus also the wings 24 enclose anangle α with the flow direction S according to FIG. 8, wherein FIG. 8represents an enlarged depiction of the encircled portion of FIG. 7.Depending on the size of the angle α, a different large surface of thewing section 30 is flown past by the cooling medium. From an idealisedpoint of view, the flown past surface varies depending on the cosine ofthe angle α, i.e. the flow past surface is at a minimum at an angle ofα=0° and is at a maximum at an angle of α=90° with respect to the flowdirection S.

FIGS. 9 to 11 show a further serpentine-shaped wing tube 20 b arrangedin the heat exchanger 1. Based on the twisting of the U-shaped sections26 (see above) the wings 24 are arranged in the wing planes F2. It ispreferred that the wing planes F2 of the serpentine-shaped wing tube 20b are arranged parallel to each other. According to a further preferredembodiment, the wings 24 are arranged in wing planes F which are notarranged parallel to each other.

As clarified by FIG. 11, the wing planes F2 and thus the wings 24 of theserpentine-shaped wing tube 20 b enclose an angle β with the flowdirection S. According to different preferred embodiments, the angle βis as large as the angle α of the adjacent serpentine-shaped wing tube20 a. It is also preferred to align the wings 20 of adjacent or ingeneral of serpentine-shaped wing tubes 20 a-20 d inserted in the heatexchanger 1 in the same or in different angles to influence in thismanner the flowing past the wing tubes 20 and thus especially theefficiency of the heat removal of the heat exchanger 1.

FIG. 15 shows a qualitative correlation between the pitch angle orsetting angle α, β of the wings 24 related to the flow direction S andthe heat W released from the heat exchanger 1. This correlation wasdetermined with a heat exchanger 1 comprising four serpentine-shapedwing tubes 20. The wing sections 30 of different serpentine-shaped wingtubes 20 a, 20 b, 20 c, 20 d are preferably arranged behind one anotherin flow direction S (cf. FIG. 4). According to a further preferredembodiment, the closer adjacent wing sections 30 of differentserpentine-shaped wing tubes 20 a, 20 b, 20 c, 20 d have a displacementof 2 mm vertical to the flow direction S with respect to each othersimilar to the arrangement in FIG. 4.

It can be seen that the heat removal starting at an angle of 10°increases continuously and reaches a maximum at 15°. For angles >15°,the heat removal decreases again until it reaches the value at around18° corresponding to a pitch angle of 10° between wing 24 and flowdirection S. Based on this correlation, it is preferred to arrange thewing 20 in an angle range of 10°≦α, β≦30°, further preferred 12°≦α,β≦18° and most preferred at an angle of α, β=15°.

According to a further preferred embodiment, the efficiency of the heatexchanger is also improved in that the wing tube has a plurality ofwings 24′, as shown in FIG. 21. These wings 24′ extend also in radialdirection to the outside. In contrast to the above described wing tubes,the wings 24′ are formed curved out of the wing planes F1, F2.Therefore, they have a cross-sectional design which is similar to thecross-section of an airplane wing. In this context, it is furtherpreferred that the wings 24′ arranged opposite to each other are curvedin different directions. This is also exemplarily shown in FIG. 21.According to a further preferred embodiment, the wings 24′ taperradially outwardly in their thickness. By means of this curved wingdesign, the heat removal between the surrounding and the medium withinthe wing tube is facilitated.

The efficiency of the heat removal of the heat exchanger may be furtherinfluenced by the arrangement of the wing sections 30 within the heatexchanger. According to a preferred embodiment, as also shown in FIG. 4,the wing sections 30 are arranged in flow direction S behind oneanother. According to a further embodiment of the present invention, thewing sections 30 of different serpentine-shaped wing tubes 20 a, 20 b,20 c, 20 d are arranged vertically displaced with respect to each otherand with respect to the flow direction S. With increasing displacementof the wing sections 30 of different serpentine-shaped wing tubes 20 a,20 b, 20 c, 20 d to each other up to a central arrangement of a wingsection 30 of a serpentine-shaped wing tube 20 b with respect to twoadjacent wing sections 30 of an adjacent serpentine-shaped wing tube 20a, 20 c, the maximum heat removal of the heat exchanger 1 is shifted tolarger angles α, β between the wing and the flow direction S (seeabove). This correlation is shown in FIG. 16. FIG. 16 shows as curve 1 anormed heat removal of a heat exchanger 1 having wing sections 30arranged behind one another with respect to the flow direction S, asshown in FIG. 4. The curve 2 shows the normed heat removal for a heatexchanger 1, wherein the wing sections 30 of a serpentine-shaped wingtube 20 b are arranged centrally displaced with respect to the wingsections 30 of adjacent serpentine-shaped wing tubes 20 a, 20 b. Thearrow in FIG. 16 illustrates how the normed maximum of the heat removalis shifted with increasing displacement of the wing sections 30 withrespect to each other up to the above described central arrangementmaximally. As soon as the wing sections of a serpentine-shaped wing tube20 b are arranged eccentric with respect to the adjacent wing section 30of an adjacent wing tube 20 a, 20 c, the normed maximum of the heatremoval between the maximum of the curves 1 and 2 is realised.

Also, it can be concluded from FIGS. 8 and 11 that the wingless curvedtube sections 40 a, 40 b are arranged in a bending plane B1, B2,respectively. The bending planes B1, B2 enclose with the adjacent tubeplanes R1, R2 the same angle as the respective wings 24 of theserpentine-shaped wing tube 20 with the flow direction S. As theelongated holes 16 in the sidewalls are adapted to the inclination ofthe wingless curved tube sections 40 a, 40 b, the elongated holes 16 arealso inclined in this angle with respect to the line vertical to theflow direction S.

LIST OF REFERENCE SIGNS

-   1 heat exchanger-   10 sidewall-   11 front plate-   14 opening-   16 elongated hole-   20 wing tube, serpentine-shaped wing tube-   22 tube-   24 wing-   24′ curved wing-   25 a recess on the inner side of the tube-   25 b web on the inner side of the tube-   26 U-shaped section-   30 wing section-   40 wingless tube section-   S flow direction-   W heat-   B1, B2 bending plane-   R1, R2 tube plane-   F1, F2 wing plane

1-34. (canceled)
 35. Heat exchanger for removing heat from a medium,wherein the heat exchanger has the following features: a. at least twoouter walls defining an opening therebetween by means of which a gasflow is directable into a flow direction, b. at least a firstserpentine-shaped wing tube including a tube and at least two wingswhich protrude radially therefrom, wherein the wing tube has at leastthree linear wing sections coupled via wingless curved tube sections, c.the wing sections of the at least first wing tube are arranged in atleast one tube plane per wing tube, which is orientated vertically tothe flow direction, wherein d. the wings of the wing sections of atleast the first wing tube are arranged in at least a plurality of firstwing planes arranged parallel to each other, wherein the wing planes arearranged in a defined angle in the range of 10°≦α≦30° with respect tothe flow direction.
 36. Heat exchanger according to claim 35, comprisingat least a second serpentine-shaped wing tube and the wing sections ofthe at least first and second serpentine-shaped wing tubes are arrangedin two tube planes per wing tube such that adjacent wing sections of awing tube are arranged in different tube planes.
 37. Heat exchangeraccording to claim 36, wherein the wings of the wing sections of thesecond wing tube are arranged in at least a plurality of second wingplanes arranged parallel to each other arranged, wherein the second wingplanes are arranged in a second defined angle in the range of 10°≦β≦30°with respect to the flow direction.
 38. Heat exchanger (1) according toclaim 37, wherein the first or the first and the second defined anglelie in a range of 10°≦α, β≦20°.
 39. Heat exchanger (1) according toclaim 37, wherein the first or the first and the second defined anglelie in a range of 12°≦α, β≦18° or at an angle of 15°.
 40. Heat exchanger(1) according to claim 36, wherein the wing sections of the at leastfirst and second wing tubes are arranged in flow direction next to eachother and/or displaced with respect to each other.
 41. Heat exchangeraccording to claim 37, wherein the wing sections of the at least firstand second wing tubes are arranged in flow direction next to each otherand/or displaced with respect to each other.
 42. Heat exchangeraccording to claim 36, comprising at least three or fourserpentine-shaped wing tubes, the wing sections of which are arranged inat least one tube plane per wing tube, respectively.
 43. Heat exchangeraccording to claim 37, comprising at least three or fourserpentine-shaped wing tubes, the wing sections of which are arranged inat least one tube plane per wing tube, respectively.
 44. Heat exchangeraccording to claim 36, wherein the wingless curved sections at a side ofthe serpentine-shaped wing tube, respectively, are arranged in aplurality of bending planes which are parallel to each other and whichextend in an angle with respect to the tube plane of the wing tube whichcorresponds to the angle of the wing plane related to the flowdirection.
 45. Heat exchanger according to claim 37, wherein thewingless curved sections at a side of the serpentine-shaped wing tube,respectively, are arranged in a plurality of bending planes which areparallel to each other and which extend in an angle with respect to thetube plane of the wing tube which corresponds to the angle of the wingplane related to the flow direction.
 46. Heat exchanger according toclaim 35, wherein the serpentine-shaped wing tubes are integral wingtubes formed of an aluminum or an aluminum alloy.
 47. Heat exchangeraccording to claim 35, the at least one serpentine-shaped wing tube ofwhich is coupled only at its starting and end point to a further conduitor a further wing tube via a separate conduit.
 48. Heat exchangeraccording to claim 36, the at least one serpentine-shaped wing tube ofwhich has a plurality of recesses at an inner side of the tube whichenlarge the surface of the inner side of the tube of the wing tube. 49.Heat exchanger according to claim 37, the at least one serpentine-shapedwing tube of which has a plurality of recesses at an inner side of thetube which enlarge the surface of the inner side of the tube of the wingtube.
 50. Heat exchanger according to claim 48, wherein the recesses onthe inner side extend in longitudinal direction of the wing tube andadjacent webs protrude radially into the interior of the wing tube. 51.Heat exchanger according to claim 49, wherein the recesses on the innerside extend in longitudinal direction of the wing tube and adjacent websprotrude radially into the interior of the wing tube.
 52. Heat exchangeraccording to claim 35, wherein a plurality of wings are formed extendingin radial direction and curved out of the wing planes.
 53. Heatexchanger according to claim 47, wherein oppositely to each otherarranged wings are curved radially outwardly in opposite directions. 54.Air conditioner having a heat exchanger according to claim
 35. 55.Cooling device having a heat exchanger according to claim
 35. 56. Solarheat device having a heat exchanger according to claim
 35. 57. Dryerhaving a heat exchanger according to claim
 35. 58. Usage of the heatexchanger according to claim 35 as condenser and/or evaporator.